In a heterogeneous reaction (where the states are varied) we do not include liquids and solids in the equilibrium equation because their concentrations do not change.
However, when it is a homogenous equation we DO include solids and liquids.
1) Why do we include liquids and solids in the Kc equation in homogeneous equilibrium equations? I get that if we didn't there would be nothing on the right hand side of Kc=.... , but why is it physically different to the case where there are varied phases?
2) What if there was an equation that involved only liquids and solids (if this is possible)? As this is a heterogeneous equation would we still not include solids and liquids? If so how would you write the Kc equation where there is nothing but solids and liquids?